Susceptors are used in microwave heating of food products to convert microwave energy to heat. They are particularly useful in connection with such products as popcorn, which does not initially respond as well as desired to the direct application of microwave energy. Susceptors are also used with products such as meat, pizza crust and other baked goods that require browning or crisping of the outer surface.
A typical susceptor includes a thin layer of microwave-interactive material, such as aluminum, that is too thin to be self supporting and is deposited on a substrate of a plastic film. However, the base sheet tends to break up, shrivel, or otherwise lose its integrity when heated. It is therefore conventional to adhesively mount the base sheet on a paper sheet, which can form a part of the structure of the container.
The adhesive used to bond a susceptor to a base sheet must retain its bonding properties and remain non-toxic when heated, and must be suitable for high volume production. These basic requirements eliminate from consideration most known, commercially available adhesives. Delamination of the susceptor from the base sheet is a problem that persists and should be avoided, particularly when the susceptor is directly exposed to the food. The need to avoid delamination may impose manufacturing requirements, particularly relating to the application of the adhesive that can be problematic on a mass production basis.
It will thus be understood that there is a need for an improved and reliable susceptor/laminate construction that readily lends itself to mass production.